Review of Maxillary Expansion Appliance Activation Methods: Engineering and Clinical Perspectives

Abstract

Objective. Review the reported activation methods of maxillary expansion devices for midpalatal suture separation from an engineering perspective and suggest areas of improvement. Materials and Methods. A literature search of Scopus and PubMed was used to determine current expansion methods. A U.S. and Canadian patent database search was also conducted using patent classification and keywords. Any paper presenting a new method of expansion was included. Results. Expansion methods in use, or patented, can be classified as either a screw- or spring-type, magnetic, or shape memory alloy expansion appliance. Conclusions. Each activation method presented unique advantages and disadvantages from both clinical and engineering perspectives. Areas for improvement still remain and are identified in the paper.

Objectively measured patient cooperation during early orthodontic treatment: Does psychology have an impact?

“…According to some authors, adherence to the doctor's orders in younger patients may largely depend on parental control and the parental approach to orthodontic treatment. 4,8,[25][26][27] Such a statement has been fully supported by the results achieved in this study. The degree of patient cooperation demonstrated a strong daily wearing time (6.09 h/day) was generally shorter compared to the instructions given to the patients.…”

Palatal Expansion and its Effects in Orthodontics

“…Also, this method of expansion places a large responsibility on the patient to comply with expansion protocols, which is a significant disadvantage of this design. Within this category of appliances is the most commonly used Hyrax appliance design, named for its trademarked Hyrax jackscrew [6].…”

“…Patient safety is also another concern, as the appliance is delivered "active". Perhaps the greatest drawback of this design is that although springs provide predictable transverse forces, any deformation of the appliance may result in unwanted force in all other planes of space [6].…”

“…The goal of magnetic expansion devices is to provide continuous forces of a lesser magnitude than traditional expansion devices. The magnets are applied so that their directionality opposes each other, thus creating a repulsive and expansive force [6]. Theoretically, this would result in a more biologically friendly and less traumatic stimulation of maxillary suture growth, similar to spring type appliances.…”

Craniofacial Stress Patterns and Displacements After Activation of Hyrax Device: Finite Element Modelling

“…Rapid maxillary expansion (RME) is one of the treatment stages of transversal discrepancy of maxilla. Fixed orthodontic devices (appliances), such as devices with the Hyrax screw or palatal distractors are recommended for the RME [2,18]. Among various types of orthodontic appliances the most hygienic ones are Hyrax devices.…”